Prepare the Vinaigrette Foundation: In a small jar or bowl, combine the minced shallots and fresh lemon juice. Let the mixture sit for 5-10 minutes to allow the acidity of the juice to mellow the raw bite of the shallots.
Craft the Emulsion: To the shallot and lemon juice mixture, add the lemon zest, minced garlic, sumac (if using), and freshly ground black pepper. Whisk thoroughly to combine. While whisking continuously, slowly drizzle in the extra-virgin olive oil until a smooth, cohesive vinaigrette forms.
Assemble the Salad Base: In a large mixing bowl, combine the rinsed and drained kidney beans, chickpeas, and the chopped Kalamata olives.
Add the Crisp Vegetables: Add the diced red bell pepper, fennel, and cucumber to the bowl with the beans.
Infuse with Herbs: Generously scatter the chopped fresh parsley, dill, and oregano over the salad.
Dress and Combine: Pour the prepared Lemon-Zest Vinaigrette over the salad. Using a large spoon or spatula, gently fold all the ingredients together until every element is evenly coated with the dressing.
Marinate and Serve: For the best flavor, cover the salad and allow it to marinate in the refrigerator for at least 30 minutes before serving. This allows the flavors to meld beautifully. Serve chilled or at room temperature.